Conventionally, an image forming apparatus employing xerography performs a developing process by supplying toner from a developer to an electrostatic latent image formed on a surface of a photosensitive drum or the like. The toner used in such a developing process is supplied from a toner case such as a toner container, an intermediate hopper and the like to the developer. The toner case is detachably mounted to the developer. For this reason, the developer is provided with a replenishing port. The replenishing port is provided in order to receive the toner from the toner case. The replenishing port is generally covered by a shutter (hereinafter referred to as “developer-side shutter”) that can be opened and closed (refer to Patent Document 1).
In addition, the toner case is provided with a case body that houses the toner. The case body is provided with a discharge port for discharging the toner to the developer.
A configurational example of the above-described developer-side shutter is shown in FIG. 15. As shown in FIG. 15, a developer-side shutter 121 is provided with a tilted face 122 that is directed obliquely upward. The developer-side shutter 121 has a substantially triangle shape in a side view. The developer-side shutter 121 is linearly slidable between a position where the replenishing port 124 is closed (see a dashed-two-dotted line) and a position where the replenishing port is open (see a solid line). The replenishing port 124 is provided in the developer 123. In a state in which the toner case (not illustrated) is not mounted to the developer 123, the developer-side shutter 121 is biased by a pair of coil springs 125 toward the position where the replenishing port 124 is closed. The pair of coil springs 125 is provided on both sides of the replenishing port 124.
In this state, if the toner case (not illustrated) is mounted to the developer 123 from an upper side as shown by an arrow in FIG. 15, the toner case presses the tilted face 122 of the developer-side shutter 121 from an upper side. And then, the developer-side shutter 121 slides linearly from the position where the replenishing port 124 is closed to the position where the replenishing port 124 is open. In other words, in such a technique, the developer-side shutter 121 is displaced in conjunction with an act of mounting the toner case to the developer 123.
In addition, a discharge port of the toner case is generally covered by a shutter that can be opened and closed. For example, Patent Document 2 discloses a toner case that is provided with a rotatable lever and a shutter that rotates according to rotation of the lever to open and close the discharge port. In addition, a gear is provided on a lever side and a shutter side, respectively. By engaging these gears the rotation of the lever is transmitted to the shutter (refer to Patent Document 2).
In the toner case thus configured, a position where the lever-side gear and the shutter-side gear engage with each other may vary due to errors in component sizes and assembling. In addition, a reaction force in directions separating from each other is applied to the position where the lever-side gear and the shutter-side gear engage with each other. This may make rotation of the lever and the shutter non-smooth, and cause tooth skipping of the gear. For solving such problems, a configuration in which thicknesses of the lever and the shutter are increased, as well as a configuration in which a cover for covering a fulcrum point of rotation of the lever and shutter is separately provided have been known.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-134452
Patent Document 2: Japanese Unexamined Patent Application Publication No. 2006-309147